Long Term Evolution (LTE) is a kind of all-IP based radio communication technology, and has become the most powerful competitor of 4G standard with high-speed uplink/downlink data transmission rate, flexible bandwidth configuration, and simplified network architecture. LTE radio interface resources are commonly shared, and signaling and data compete for the commonly shared resources simultaneously for transmission. Currently, the radio resource scheduling schemes which may be used for Voice over LTE (VoLTE) include dynamic scheduling, semi-persistent scheduling and group scheduling, and the like. Dynamic scheduling is a universal scheduling method. For each basic unit of radio resource scheduling, Physical Resource Block (PRB), the scheduler may assign a resource according to a resource request of the User Equipment. Semi-persistent scheduling is a scheduling method aiming at real time services including VoLTE which may reduce signaling overhead and increase system capacity.
The output rule of voice data packet is shown in FIG. 1. In a stage with no call, no voice packet needs to be scheduled, so dynamic scheduling of other data services may be conducted, such as File Transfer Protocol (FTP) or User Datagram Protocol (UDP). In a call stage, a sampling packet will be produced in every 20 ms when users are calling. Therefore, generation of the voice message of user is predicable. Under such circumstance, semi-persistent scheduling may be adopted to avoid performing dynamic scheduling each time, thereby improving the voice transmission capacity by about 20%. In a stage of call interval, theoretically, a background sound symbol will be produced in every 160 ms, and there is no voice data scheduling. When a voice service starts, dynamic scheduling mode is adopted for scheduling, and determining whether the semi-persistent scheduling is enabled and whether the User Equipment (UE) supports the semi-persistent scheduling mode, if the semi-persistent scheduling mode is enabled and the UE supports the semi-persistent scheduling mode, then the UE will be configured for scheduling in semi-persistent scheduling mode; otherwise, dynamic scheduling mode will be used for scheduling. According to 3GPP specification, the level range of uplink/downlink Modulation and Coding Scheme (MCS) of dynamic scheduling is 0˜28; during each scheduling, Downlink Control Information (DCI) is issued, so resource overhead of Physical Downlink Control Channel (PDCCH) is big. The MCS level range of semi-persistent scheduling is 0˜15, and DCI only needs to be issued each time when semi-persistent scheduling is activated or deactivated, so PDCCH overhead is small. When the channel condition is very good, when 15 PRBs are scheduled, the dynamic scheduling level is 28, and the size of source block scheduled is 11064, while the MCS level of semi-persistent scheduling is 15, and the size of the source block scheduled is 4264, which is almost 2.5 times of the source block size of semi-persistent scheduling. Therefore, dynamic scheduling and semi-persistent scheduling have their respective strengths and weaknesses. Dynamic scheduling may schedule a higher modulation and coding level, but PDCCH resource overhead is big. Semi-persistent scheduling has the least PDCCH resource overhead, but the maximum MCS level of scheduling is 15. Both dynamic scheduling mode and semi-persistent scheduling mode may be simply realized, but the flexibility is poor, the strengths of semi-persistent scheduling mode and dynamic scheduling mode can't be displayed simultaneously, and PDCCH resources can't be assigned rationally, which reduces the total capacity of the base station.